Andreev reflection in a Y-shaped graphene-superconductor device
Andreev reflection in a Y-shaped graphene-superconductor device
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Y 形石墨烯超导体装置中的安德烈耶夫反射
DOI：
10.1103/physrevb.98.035403
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发表时间：
2017-12
影响因子：
3.7
通讯作者：
Li Yu-Xian
中科院分区：
文献类型：
--
作者：
Wang Chao;Zou Yonglian;Song Juntao;Li Yu-Xian
利用非平衡绿色函数方法，在紧束缚模型下研究了Y型石墨烯-超导体器件中的Andreev反射.考虑到锯齿形和扶手椅终端，我们确认锯齿形终端是更好的选择，用于检测Andreev反射没有外部场。由于有限尺寸中心区域的边界散射，Andreev逆反射和镜面反射之间的差异很难区分。虽然通过调节器件的尺寸可以使这种差异变得明显，但是通过输运电导来定量区分它们仍然是不可能的。当在中心区域施加垂直磁场时，使入射电子和反射空穴沿边缘或界面沿着传播，从而避免了这个问题。在这种情况下，来自不同频带的回射孔和镜面反射孔具有相反的有效质量，因此一个的移动方向与另一个相反。反射的空穴流到哪个外部终端完全取决于Andreev反射的类型。因此，即使对于有限尺寸的器件，在强磁场的存在下，镜面Andreev反射也可以与逆反射明显区分。
Using the non-equilibrium Green function method, we study the Andreev reflection in a Y-shaped graphene-superconductor device by tight-binding model. Considering both the zigzag and armchair terminals, we confirm that the zigzag terminals are the better choice for detecting the Andreev reflection without no external field. Due to scattering from the boundaries of the finite-size centre region, the difference between Andreev retroreflection and specular reflection is hard to be distinguished. Although adjusting the size of the device makes the difference visible, to distinguish them quantitatively is still impossible through the transport conductance. The problem is circumvented when applying a perpendicular magnetic field on the centre region, which makes the incident electrons and the reflected holes propagate along the edge or the interface. In this case, the retroreflected and specular reflected holes from the different bands have opposite effective masses, therefore the moving direction of one is opposite to the other. Which external terminal the reflected holes flow into depends entirely on the kind of the Andreev reflection. Therefore, the specular Andreev reflection can be clearly distinguished from the retroreflected one in the presence of strong magnetic field, even for the device with finite size.
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影响因子：
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通讯作者：
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